my brute-force routine:
(number of points in each of the 2 dimensions, with the integral following it)

100 2.42e-5
200 1.482e-5
300 1.1787e-5
400 1.02982e-05
500 9.41893e-06
600 8.8409e-06
700 8.43315e-06
800 8.13081e-06
900 7.89813e-06
1000 7.7138e-6
1500 7.17363e-06
2000 6.9136e-06

my adaptive routine:     totpts: 1547,  6.23812e-06
matlab adaptive routine: totpts:  197,  3.05815e-05


conclusion: mine is right, and matlab is wrong.